The furious family of murdered Sophie Toscan du Plantier have demanded French police take over the case in the wake of the Garda bugging scandal.

Sources close to Sophie’s parents, Marguerite and Georges Bouniol, have revealed they are distraught by new evidence that gardai bungled the probe.

A friend of the elderly Parisian couple told the Irish Sunday Mirror: “They want to know what happened to their daughter.

“Gardai have had 17 years to find out the truth about Sophie but they haven’t given the family any answers.

“Now questions have been raised about the way they conducted their investigation.

“There are allegations of conversations being taped illegally, of one witness being intimidated and another being bribed. It’s about time French police took over. That’s what the family want. Gardai have lost all credibility and the evidence that was collected can’t be trusted.”

Mum-of-one Sophie, 39, was battered to death outside her holiday home near Schull, West Cork, on December 23, 1996.

Ian Bailey (Photo: AFP/Getty Images)

British journalist Ian Bailey was arrested twice in connection with the brutal killing and released without charge on both occasions.

Bailey, who is originally from Manchester, won an appeal against extradition to France to be questioned by local authorities in 2012. He is now suing the State for alleged wrongful arrest, claiming gardai conspired to implicate him in the murder case.

As part of his lawsuit, Mr Bailey’s legal team have requested all investigation documents be handed over.

Meanwhile, it has emerged gardai secretly recorded at least 133 phone conversations from 1997.

The tapes include internal discussions between officers, conversations between detectives and witnesses, and talks between gardai and journalists.

It is understood the material could shed light on claims made by witness Marie Farrell that she was pressurised by gardai to identify a man she saw near the murder scene as Mr Bailey.

Marguerite Broussons the mother of Sophie Toscan Du Plantier who was murdered in West Cork Ireland upon his arrival at Cork airport

It is also believed the recordings could shed light on the claims by former British soldier Martin Graham that he was paid in cash and drugs to frame Mr Bailey.

Speaking exclusively to the Irish Sunday Mirror earlier this year, Graham alleged gardai gave him cannabis to help him get close to Mr Bailey.

In a taped interview made in 1997, obtained by this paper, Mr Graham also claimed he was offered IR£5,000 to get Mr Bailey to confess to Sophie’s murder. Mr Bailey’s lawsuit has been adjourned until May 9 but a full hearing will not take place before November.

Sophie’s uncle Jean-Pierre Gazeau, who is also the president of Assoph (the association for the truth about Sophie’s murder), insisted that evidence of Garda wrongdoing should not take the focus away from the murder investigation.

He told the Irish Sunday Mirror: “It would really be a catastrophe, yet another one, if the Garda’s misconduct totally distracted from what is for us the main and constant concern – the truth and fair justice in Sophie’s case.

“The whole political, judicial and media community in Ireland should put that noble cause as the first priority.” Jean-Antoine Bloc-Daude, Assoph’s vice- president, added: “We’re seeking the truth – we are not looking to lock up a possibly innocent person.

“French detectives will travel to Ireland in May to continue their own inquiry under the guidance of investigative French magistrate, judge Patrick Gachon.

“Judge Gachon will make a formal request for the taped conversations.

“At the moment we are being drip-fed information, so we would like this to go ahead as soon as possible.”